LONDON, Sep 21 (IPS) - The first visit by an Amnesty International team to Darfur over the last several days showed that the U.S. human rights record has weakened its case to intervene in a human rights crisis elsewhere. ''It has made it much harder for the U.S. to take on its self-described role as human rights leader,'' executive director for Amnesty International U.S. Bill Schulz told IPS. Schulz, who returned from a visit to Darfur Tuesday as a member of an Amnesty team said the visit showed that ''the U.S. loses an effective voice as a moral force in...